Finding EntropY Using Experimental Data

[anasofia]

Hi! I know the test is past but this would help my understanding a lot if someone could explain: One of the questions was something about finding the entropy of a particular molecule (I think C6H5 something something) at a specific heat. I could not figure our how to do it based solely on the data given in the problem so I looked at the data sheet and there were Standard Molar Entropy's for things, but none for the listed molecule. I know that entropy is a state function and can therefore be added/subtracted, but I was under the impression that that is only for equations where things can cancel out, I am not sure how to combine molecules in order to find other entropies, or even if that's how one is meant to solve the problem.

[alexandra]

So entropy approaches zero as the temperature approaches 0 kelvin. I had thought the answer was zero but apparently theres some residual entropy that arises from the fact that the molecule is not a perfect crystal and there is some movement within the molecule. Hope this helps!

[Brandon Li]

Use Boltzmann's formula, S (entropy) = kB (boltzmann's constant) * ln W where W = possible orientations of the molecule ^ amount of molecules (usually given as 1.0 mols so 6.022 x 10^23)